Foundation underreamer



Aug. 17, 1965 E. G. BRASHEAR 3,200,894

FOUNDATION UNDERREAMER Filed Dot. 29, 1963 2 Sheets-Sheet 1 INVENTOR.

30j EDWIN G. BRASHEAR A TTORNEYS' Aug. 17, 1965 E. G. BRASHEAR 3,200,894

FOUNDATION UNDERREAMER Filed oct. 29, 1965 2 sheets-sheet 2 FIG] FIGS l IIIII) FI 6 INVENTOR.

EDWIN G. BRASHEAR A TTORNE YS United States Patent O 3,200,894 FUUNDATIUN UNDERREAMER Edwin G. Brashear, Dallas, Tex. (1612 Eagle Hill rrail, Longview, Tex.) Filed (ict. 29, 1963, Ser. No. 319,88) 7 Claims. (Cl. 155-286) This invention relates to underreamers and more particularly to a foundation rearner capable of cutting rock and other hard materials.

Upon drilling a bore hole for the formation of a foundation pier, it is the practice to underream the surrounding earth at the bottom of the bore to provide a bell shaped opening which will enable the formation of a relatively large supporting base for the `foundation pier. The underreamers presently employed usually have a plurality of blades extending longitudinally of the bore hole, these blades being pivotally mounted at their upper ends and adapted to swing outwardly upon rotation of the reamer by the kelly, The underreams are relatively large in view of the fact that the bore holes themselves may range anywhere from about l ft. on up to l2 ft. or more in diameter, and the underrearns usually have about twice the diameter of the bore.

The bell shaped underreams may be cut so that the side walls are disposed anywhere from about 45 to 60 to the vertical. With the prior art underreamers, the blades engage they complete height of the underream, and consequently are subject to overloading when operating in relatively hard material such as rock. This frequently results in breakdowns of the drilling rig, particularly due to the stripping of the teeth of the rotary tables and drive gears therefor. Consequently, where the underream is to be cut into rock and other hard material, the known underreamers cannot be used and it is the general practice to cutout these underreams by manually operated jack hammers. rihis manual operation is very time consuming and costly.

Having in mind the defects of the prior art apparatus, it is an obiect of the present invention to provide a foundation underreamer that is capable of efficient operation in all types of earth surrounding a bore hole.

It is another object of the invention to provide a foundation underreamer that will operate etiiciently in cutting rock and other hard material without subjecting the drilling machinery to undue stresses and strains.

It is a further object of the invention to provide a foundation underreamer wherein the blades are arranged to take relatively small bites of the surrounding soil and thereby are able to cut into rock without severe stresses or strains on the drilling machine.

lt is still another object of the invention to provide a foundation underreamer having simplicity of design, econ omy of construction and efficiency in operation.

Briefly, a foundation underreamer in accordance with the present invention comprises a generally cylindrical framelike body of 'a diameter approximating that of the bore hole and provided with a diametrically disposed, verticaliy extending pathway within which a diametrically arranged blade carrier is slidably mounted for` vertical movement. The top of 'the body portion is provided with an opening for passage of the kelly or drill rod, and a kelly box or socket for receiving the lower end of the drill rod is xed to the top of the blade carrier. A pair of blades are slidably supported by the blade carrier for movement generally radially of the body portion and the body portion is provided with oppositely disposed cam tracks extending the height thereof.

Cam followers secured to the blades cooperate with the cam tracks whereby the blades are forced outwardly as the carrier is lowered within the body portion by the 3,2%,894 Patented Aug. l?, 1955 lowering of the kelly or drill rod. As the underreamer is rotated by the kelly and the blades are forced outwardly, they underrearn the surrounding soil and the cuttings are collected in a pan at the bottom of the body portion. Periodically, the underreamer may be lifted from the bore hole by raising the kelly which thereby retracts the blades within the cylindrical contines of the body portion to enable lifting the reamer to dump the cuttings which may be elfected either by a trap door bottom or by spinning the rearner which serves to centrifugally discharge the cuttings from the bottom pan.

The novel features that are considered characteristic of the invention are set forth with particularity in the appended claims. rThe invention itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof, will best be understood from the following description of a specific embodiment when read in connection with the accompanying drawings, wherein like reference characters indicate like parts throughout the several figures and in which:

FG. 1 is a view in perspective of a foundation underreamer in accordance with the present invention;

FiG. 2 is a side view in elevation of the underreamer shown in FlG. l disposed at the bottom of a bore hole prior to underreaming operation;

FIG. 3 is .a cross-sectional View taken on line 3-3 of FlG. 2;

FlG. 4 is anenlarged fragmentary cross-sectional View taken on line @-4 of PEG. 3;

FiG. 5 is a side view in elevation of the underreamer viewed at right angles from that of FIG. 2;

FIG. 6 is an enlarged exploded view of the blade carrier and blades, and

FIG. 7 is an elevational side view similar to FIG. 2, but illustrating a partially cut underream.

Referring now to the drawings in detail, specifically to FlG. l, a foundation underreamer according to the present invention comprises la body portion l@ including a bottom catch pan l2, a top plate i4 and at least two pairs of uprights lo, i6 and 18, i3 rigidly connecting the bottom pan and the tcp plate. The uprights of each pair are uniformly spa-ced from each other and the two pairs are diametrically disposed so as to define a vertically extending, diametrically arranged pathway for a blade carrier 20.

The blade carrier 2t? extends diametrically of the body portion 10 with its end portions respectively fitting slidalbly between the uprights i6, 16 and i8, 18" of each pair. The carrier 20 is movable vertically in the pathway dened `by the uprights and preferably a pair of rollers 22 are journaled on each end of the carrier for rolling engagernent with the respective uprights to prevent deviation of the carrier diametrically of the body portion, The top plate 14 is provided axially thereof with a hole 24 for passageof the kelly or drill rod 261 and a kelly recess box 2d is xed on the upper surface of the carrier 20 for the reception of the lower end of the kelly, the two being releasably secured by a pin Sti. Usually the kelly 26, hole 24 and kelly box 28 are of square or other noncircular section and configuration to transmit rotational drive from the kelly to the rearner.

The sides of the carrier Ztl are each provided with a recess 32 along its lower edge portion and also with a longitudinal slot 34 within each recess, A blade 35, having an inwardly directed flange 38 along its top, is slidably mounted in each recess 32 with its ange nested in the slot 34. The blades 36 extend below the carrier 20 and along their lower edges are provided with inwardly extending cutting edges dt) .such as a grader steel blade or, as shown, a plurality of teeth which, if desired, may be removably mounted in known manner in pockets 42 and secured Aby bolts 44. Preferably, a plurality of teeth are disposed along the lbottom of each blade and at least one f 3 such tooth is mounted at the outer end of each blade. The teeth may be positioned at any selected angle.

Each blade 35 is provided with an internally threaded bore extending transversely therethrough for the reception of a cam follower. Preferably, as best shown in FIG. 4, the blade is provided with a smooth walled bore 46 for the reception of a bolt d8 Which is threaded into a nut 5d and secured by a lock pin 52. Preferably, the nut Sli is welded or otherwise rigidly fixed to the inner surface of the blade 36, and holds the bolt liti rigidly to prevent binding of a cam follower roller 54 journaled on the bolt between the bolt head and the outer surface of the blade. As best shown in FIG. 6, each blade 3&5 may be provided with a plurality of boit holes i6 spaced longitudinally of the blade so that the bolt 48 may be selectively mounted to regulate the extension of the blade from the body portion It).

.The movement of the blades 3e relative to the body portion It) is controlled by two cams 55, 5d disposed diametrically opposite each other on said body portion it? for respective cooperation with the cam follower roller 5d on the adjacent blade. Conveniently, each of the cams may comprise a spaced pair of metal bars 58 extending from the juncture between the top i4 and an upright of 'one pair of the juncture of the corresponding upright of the other pair with the bottom pan l2. More specifically, the bars dit forming the cam Se extend from the top of the upright ld to the bottom of the upright lil, and the .bars 5S forming, the cam 56 similarly extend from the top of the upright 18 to the bottom of upright lid.

The cam forming bars 5S are coplanar with the uprights to which they are secured and therefore serve, along with said uprights, as lateral guides for the Sides of the carrier 29 and, more particularly, for the respective blades 36. Moreover, the cams 55, 56' may have any desired configuration for forming curved or straight sided underrearns, andthey may be positioned at any selected angle. The majority of underreams are cut at an angle of approximately 60, as illustrated in FIG. 7 and indi- -cated by phantom lines in FIG. 2. However, it is not unusual to require 45 cuts under some conditions, such as type of soil, weight to be supported and the like.

The body portion 10 is primarily a cylindrical frame, the bottom pan l2 yand top plate I4 being circular and having a diameter substantially equal to that of the bore hole within which the reamer i-s to be operated. The bottom pan 12 is provided with upstanding side walls 6@ contiguous with its periphery and extending only between the corresponding uprights of the two pairs I6, lo' and t8, I8. Similarly, the top plate is provided with a depending skirt 62 contiguous with its periphery and the bottom edge of this `skirt is engaged by the carrier rollers 22 in the upper position of the carrier, and thereby help balance the load of the reamer on the kelly 26. Both the pan walls 60 and the skirt 62 serve not only to brace the structure, but also to guide the reamer in its pass-age through the bore hole.

In operation, when a foundation bore hole B is drilled `to the desired depth, the drilling rig is operated to lift the kelly 26 above ground, the drill bit is removed from and the reamer attached to the lower end of the kelly. When the reamer i-s at rest, the blade carrier 2t? gravitates onto the bottom pan 12, and the blades 36 are extended by the cam followers 54 in the earns 56, 56. Thus, to connect the kelly 26 with the reamer, the lowed end of the kelly is lowered through the hole 24 in the top plate 14, is nested in the kelly box 28 and is secured by the pin 30. Thus, the blade carrier 2t) is connected directly to the kelly.

As the kelly is lifted, it lifts the carrier 2t?, the followers 5ft cooperating with the cams 55, Se' to retract the blades 36, until the kelly box 2S engages the underside of the top plate 14- and/ or the rollers 22 engage the bottom edge of the top plate skirt 62. Further elevation or" the kelly lifts the whole reamer, including the body portieri,

E so that it can be aligned with the bore hole B and lowered thereinto. As the reamer is lowered in the bore B, the pan side walls 60 and top and top skirt 62 serve to guide the reamer in its movement.

When the bottom pan` engages the bottom of the bore B, as shown in FIG. 2, the kelly 215 is then rotated to drive the reamer, and simultaneously the kelly is also forced downwardly to depress the blade carrier 2d. As the carrier is lowered, the followers 54 cooperating with the cams 56, 56 force the blades 36 outwardly `so that their cutting edges itl engage and undercut the walls of the bore B at a gradually increased degree. The rollers 22 engaging the two pairs of uprights in, t6 and i8, i8 restrain the carrier from radial deviation so that the cutting operation is uniform in all directions.

When the oper-ation has been suiiicient to lill the bottom pan I2 with cuttings, the kelly is lifted, as previously described, to lift the reamer from the bore B. Relatively large diameter reamers may have a hinged dumping bottom, but ordinary reamers, of two to three foot diameters, may have iixed bottoms as they may be readily `emptied. merely by spinning the kelly and reamer, whereby the cuttings are discharged by centrifugal action. The kelly may then again be lowered to continue the cutting operation until a complete undercut U is produced, as partially shown in FIG. 7.

Obviously, the size of the undercut U can be reg' lated by the selective mounting of the cam follower bolts 48 in the blade bores 46. In some circumstances, a smaller than maximum undercut may be suiiicient. On the other hand, when working in very hard rock, it may be advantageous to undercut in stages. In the first stage, the bolts d8 may be located inthe'bores 46 nearest the outer cutting ends of the blades 35 so that the latter would be projected only a limited distance. In subsequent stages, the bolts 43 can be located in successive bores 46 so that the blades will successively be projected outward a greater distance.

Although a certain specific embodiment of the invention has been shown and described, it is obvious that many modifications thereof are possible. The invention, therefore, is knot to be restricted except insofar as is necessitated by the prior art and by the spirit ofthe appended claims. l

That which is claimed is:

l. A foundation reamer for attachment to a drill stem comprising a frame including a circular bottom pan having a diameter substantially equal to that of the bore hole to be undercut, said frame also including a top plate and two pairs of vertically disposed brace bars extending between and rigidly secured to said pan and plate, said top plate having a centrally disposed opening for the passage of a drill stem, said pairs of brace bars being disposed respectively on opposite sides of said frame and the bars of said pairs being substantially uniformly spaced on opposite sides of a diameter yof said pan, a vertically movable blade carrier extending diametrically of said frame with its ends disposed respectively between said pairs of bars, means on said carrier centrally thereof for rigid attachment to the lower end of a drill stem, a pair of blades slidably mounted on said carrier for movement generally radially of said frame, cutting means on the outer end portions of said blades, cam guides on opposite sides of said frame and extending angularly between the bars of said pairs on the same side of said frame, and a cam lfollower ron each of said blades and engaged in a respective cam guide.

2. A foundation reamer according to claim l wherein said blades each have a plurality of sockets spaced longitudinally thereof, and the cam follower for each blade is adapted to be selectively mounted in one socket of each blade.

3. A foundation reamer according to claim 1 wherein said circular pan has upstanding yside walls extending at least partially therearound for collecting loose material.

4. A foundation reamer according to claim 1 comprising guide means on the ends of said carrier and engageable with the respective pairs of bars to brace said carrier against movement laterally of said frame.

5. A foundation reamer according to claim 4 wherein said guide means comprises a pair of rollers journaled on each end of said carrier and disposed laterally thereof for engaging the respective bars.

6. A foundation reamer according to claim 4 wherein said cutting means comprises cutting teeth removably mounted along the bottom edges of said blades.

7. A foundation reamer according to claim 6 wherein said cutting means comprises at least 'one cutting tooth removably mounted on the outer end of each of said blades.

References Cited by the Examiner UNITED STATES PATENTS CHARLES E. OCONNELL, Primary Examiner. BENJAMIN BENDETI, Examiner. 

1. A FOUNDATION REAMER FOR ATTACHMENT TO A DRILL STEAM COMPRISING A FRAME INCLUDING A CIRCULAR BOTTOM PAN HAVING A DIAMETER SUBSTANTIALLY EQUAL TO THAT OF THE BORE HOEL TO BE UNDERCUT, SAID FRAME ALSO INCLUDING A TOP PLATE AND TWO PAIRS OF VERTICALLY DISPOSED BRACE BARS EXTENDING BETWEEN AND RIGIDLY SECURED TO SAID PAN AND PALTE, SID TO PLATE HAVING A CENTRALLY DISPOSE OPENING FOR THE PASSAGE OF A DRILL STEM, SAID PAIRS OF BRACE BARS BEING DISPOSED RESPECTIVELY ON OPPOSITE SIDES OF SAID FRME AND THE BARS OF SAID PAIRS BEING SUBSTANTIALLY UNIFORMLY SPACED ON OPPOSITE SIDES OF A DIAMETER OF SAID PAN, VERTICALLY MOVABLE BLADE CARRIER EXTENDING DIAMETRICALLY OF SAID FRAME WITH ITS ENDS DISPOSED RESPECTIVELY BETWEEN SAID PAIRS OF BARS, MEANS ON SAID CARRIER CENTRALLY THEREOF FOR RIGID ATTACHMENT TO THE LOWER END OF A DRILL STEM, A PAIR OF BLADES SLIDABLY MOUNTED ON SAID CARRIER FOR MOVEMENT GENERALLY RADIALLY OF SAID FRAME, CUTTING MEANS ON THE OUTER END PORTIONS OF SAID BLADES, CAM GUIDES ON OPPOSIT SIDES OF SAID FRAME AND EXTENDING ANGULARLY BETWEEN THE BARS OF SAID PAIRS ON THE SAME SIDE OF SAID FRAME, AND A CAM FOLLOWER ON EACH OF SAID BLADES AND ENGAGED IN A RESPECTIVE CAM GUIDE. 